An ink-jet recording device includes an ink-jet recording head and a carriage. The carriage reciprocates in a direction substantially orthogonal (hereinafter, referred to as an “orthogonal direction”) to a feeding direction of a recording sheet (sheet member). An ink-jet recording head is mounted on the carriage. In the ink-jet recording device, while the recording sheet is being fed below the ink-jet recording head along a predetermined sheet feeding path, the ink-jet recording head selectively ejects droplets of ink, as the carriage reciprocates in the orthogonal direction. The ink droplets adhere onto the recording sheet, thereby recording an intended image on the recording sheet.
In the ink-jet recording device, a recording sheet sometimes has a paper skew with respect to the sheet feeding direction when the recording sheet is fed along the sheet feeding path. If an image is recorded in a state that the recording sheet is slanted, the recorded image is slanted with respect to the four edges of the recording sheet.
The paper skew of a recording sheet can be detected, for example, by a method described in Japanese Utility Model Application Publication No. H04-84245. Japanese Utility Model Application Publication No. H04-84245 discloses that a skew amount of the recording sheet is detected based on the positions of the side edges of the recording sheet in the orthogonal direction before the recording sheet is fed to and below a printing unit. Specifically, the carriage includes two reflection sensors provided at a distance away, from each other in the feeding direction. While the carriage reciprocates in the orthogonal direction, the reflection sensors detect the positions of both side edges of the recording sheet in the orthogonal direction before the recording sheet is fed to and below a printing unit. The skew amount of the recording sheet is obtained based on the detected result. Another method is also described in Japanese Utility Model Application Publication No. H04-84245. The carriage includes one reflection sensor. While the carriage reciprocates in the orthogonal direction at a specific portion of a recording sheet, the reflection sensor detects the positions of both side edges of the recording sheet before the recording sheet is fed to and below a printing unit. The recording sheet is then fed a prescribed distance from the specific portion in the feeding direction, so that the reflection sensor detects the both side edge positions of the recording sheet again in the same manner at another portion of the recording sheet. The skew amount of the recording sheet is obtained based on these detected results.
In the ink-jet recording device described in Japanese Patent Application Publication No. 2004-90316, a reflection-type photointerrupter is mounted on a carriage. As the carriage reciprocates for the first cycle, the photointerrupter detects the positions of both side edges of the recording sheet in the orthogonal direction. As the carriage reciprocates for the second cycle or later, the reflection-type photointerrupter detects the position of one side edge. The other side edge position of the recording sheet in the orthogonal direction is calculated accurately based on the detected result.